It looks like large embedded images have a max display resolution of 1080 pixels wide. This allows people to see the full width of the image without having to scroll. To see the full resolution image, we have to click on it.
Could a limit also be applied to the vertical display resolution of high-res photos? People browsing on their phones probably have no issues. But people browsing on desktops and laptops have to scroll down just to see the whole image. Also, scrolling through an image-heavy thread can be a bit exhausting, especially if I'm just trying read comments sandwiched between so many high resolution photos.